Posted: August 1, 2018

This is the 10th of eleven short news articles written by students, during the professional development class. This year we had the students interview their advisor(s), in an effort to help them better understand the larger context of their projects.

Always Adapting: Disease Dynamics in Plant-Pollinator Systems
By Chauncy Hinshaw

Disease is often studied as a binary system, consisting of a pathogen and a single host. However, often disease-causing organisms can infect more than one type of host, and even hosts drawn from distant branches of the tree of life. As an example, researchers have recently identified several plant viruses in bees! What are they doing there? Here at Penn State, scientists are currently hard at work untangling these complex interactions to preserve the health of plants and pollinators alike.

Dr. Cristina Rosa values the complexity of virus interactions and studies plant disease with a broad mindset. Plants and pollinators both develop mechanisms to combat infection by bacteria, fungi, and viruses. However, "through evolution these disease agents can develop resistance to host defenses. There is a constant arms race taking place between organisms and the things that make them sick" says Rosa. Viruses with multiple hosts must adapt to avoid defenses from all of their hosts, and each host may have a different way of dealing with virus infection.

The plant viruses associated with bees are interacting with both insects and plants, which are in constant contact with each other. In many agricultural systems, the low genetic diversity of the cultivated plants may lead to limited defense responses. This could mean a better chance for viruses to overcome the defenses of their plant hosts, and an increased likelihood of disease.

Are these plant viruses simply passing through bees, taken in from the pollen and nectar they consume? Some researchers have hypothesized that a few plant viruses have evolved to infect and cause disease in bees. Working with several of Penn State's pollinator researchers, Dr. Rosa hopes to assess the diversity of plant viruses associated with pollinators and to find novel viruses that could be the evolutionary link between plant and insect infecting viruses. Additionally, if pollinators serve merely as carriers of plant viruses, are viral diseases in plants having significant effects on bee health?

Studying such dynamic disease interactions requires thinking about these systems in new ways. Researchers are now blending ideas from different fields to evaluate the health of organisms in response to different stressors, and their ability to adapt to change.